Machines for compression molding closure shells, or compression molding sealing liners within closure shells, typically include a turret or carousel that rotates around a vertical axis. A plurality of molds are provided around the periphery of the carousel, in the form of male and female mold sections that are aligned along vertical axes parallel to the axis of rotation. Cams drive one or both of the mold sections of each pair between an open position, in which a molded part is stripped from the mold and a charge of molten plastic material is placed into the mold, and a closed position in which the mold sections are brought together to compression mold the shell or liner. In a liner machine, premade shells are placed in a nest when the mold sections are open, and a charge or pellet of liner material is placed within the mold before the mold is closed. U.S. patents that illustrate machines of this type for compression molding plastic closure shells include U.S. Pat. Nos. 5,670,110, 5,989,007, 6,074,583 and 6,478,568. U.S. patents that illustrate machines of this type for compression molding sealing liners within closure shells include U.S. Pat. No. 5,451,360. U.S. application Ser. No. 11/109,374 discloses a vertical wheel compression molding machine, which rotates around a horizontal axis, for compression molding closure shells or sealing liners within closure shells.
The present disclosure involves a number of aspects that can be implemented separately from or in combination with each other.
An apparatus for placing mold charges into a mold of a compression molding machine, in accordance with one aspect of the present disclosure, includes a carrier, an arm pivotally mounted on the carrier and a mold charge pick-up cup on the arm at a position spaced from the carrier. The arm is pivotal on the carrier between a first position at which the arm is positioned to deposit a mold charge into a mold and a second position at which the mold charge pick-up cup is disposed to transport the mold charge. The carrier preferably is mounted for rotation around an axis. In some embodiments, a cam mechanism is coupled to the arm to pivot the arm as a function of rotation of the carrier. A spring may be coupled between the arm and the carrier for biasing the arm toward one of the first and second positions of the arm. In another embodiment, an actuator is carried by the carrier and coupled to the arm to pivot the arm with respect to the carrier. The arm preferably includes a passage for selective application of air and/or vacuum to the mold charge pick-up cup.